Blinking two LEDs in and out of phase

Projects Programming
37

how does it possible to write just unsigned?
how does the program know if you meant unsigned integer or long or ?

edit:
is there a elegant way to prevent from the Serial.print(cycleCount) to print only 1 number on each count?

void loop() 
{
  Serial.println(cycleCount);
  static unsigned long timer = 0;